|Popular Mechanics, Aug 1911, p. 107|
Railroad dynamometers were typically built into a special-purpose car, which is why we have not seen any turn up at a pen show, or on eBay for that matter. Waterman advertisements continued to make period mention of their pens' use in dynamometers for some years. The ad below ran in Scientific American, vol. 122 (May 1, 1920), p. 500, as well as Collier's, vol. 65 (May 22, 1920), p. 47 and others.